Mercury (Hg(2+)) Detection in Aqueous Media, Photocatalyst, and Antibacterial Applications of CdTe/ZnS Quantum Dots.

In the present work, CdTe/ZnS high luminescence quantum dots (QDs) were synthesized by a facile, fast, one-pot, and room temperature photochemical method. Synthesized QDs were characterized by different structural and optical analyses such as X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDS), field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), Fourier transform-infrared spectroscopy (FT-IR), Raman, photoluminescence (PL) and UV-visible (UV-vis) spectroscopies. The results confirmed the successful growth of the ZnS shell and formation of CdTe/ZnS core/shell structure. CdTe/ZnS prepared QDs indicated a PL quantum yield of about 51%. These high luminescence QDs were used for detection of Hg2+ ions in aqueous media, as catalyst for photodegradation of different organic dyes, and as antibacterial material for the inhibition of bacterial growth. PL intensity of the CdTe/ZnS QDs was completely quenched after addition of 1 m molar Hg2+in to the media. Photocatalyst activity of CdTe/ZnS QDs was studied by rhodamine b, methylene blue, and methylene orange as organic dyes under both the sun and UV illuminations, and results showed that CdTe/ZnS QDs had the best photocatalyst activity for methylene blue degradation under UV irradiation and radical scavenger results indicated that electrons have a main role in photodegradation of methylene blue dye by CdTe/ZnS QDs under UV illumination. Antibacterial effects of CdTe/ZnS QDs evaluated by Minimum Inhibitory Concentration (MIC), and Minimum Bactericidal Concentration (MBC) methods against two strains of bacteria. The results of the antibacterial test showed that CdTe/ZnS could inhibit bacterial growth in Bacillus cereus (Gram-positive) and Escherichia coli (Gram-negative G) bacteria.

Molaei M ，Farahmandzadeh F ，Hemmati R 《-》

Aqueous synthesis of highly stable CdTe/ZnS Core/Shell quantum dots for bioimaging.

In this work, we report the synthesis, characterization and biological application of highly stable CdTe/ZnS (cadmium tellurite/zinc sulphide) Core/Shell (CS) quantum dots (QDs) capped with mercaptosuccinic acid (MSA). The CS QDs were synthesized using a simple one-pot aqueous method. The synthesized CdTe/ZnS CS QDs were found to exhibit excellent stability even 100 days after preparation and also showed better photoluminescence quantum yield (PLQY) of about 50% compared with that of only CdTe QDs which was nearly 12%. The formation of the CdTe/ZnS CS was confirmed by high-resolution transmission electron microscopy (HR-TEM), and Fourier transform infra-red (FTIR) and X-ray diffraction (XRD) analyses. Further, on extending our study towards bioimaging of E. coli cells using the QDs samples, we found that CdTe/ZnS CS QDs showed better results compared with CdTe QDs.

Saikia D ，Chakravarty S ，Sarma NS ，Bhattacharjee S ，Datta P ，Adhikary NC ... -  《-》

Ultraviolet radiation synthesis of water dispersed CdTe/CdS/ZnS core-shell-shell quantum dots with high fluorescence strength and biocompatibility.

Xu B ，Cai B ，Liu M ，Fan H ... -  《-》

Design and synthesis of highly luminescent near-infrared-emitting water-soluble CdTe/CdSe/ZnS core/shell/shell quantum dots.

Zhang W ，Chen G ，Wang J ，Ye BC ，Zhong X ... -  《-》

Structural, luminescent and antimicrobial properties of ZnS and CdSe/ZnS quantum dot structures originated by precursors.

ZnS quantum dots (QDs) and their core/shell (CdSe/ZnS) structures were studied for Zn based precursor reactivities. ZnS and CdSe/ZnS QDs were prepared selecting aqueous route and then characterized via XRD, TEM, EDX, PL, RAMAN and FTIR practices. Core/shell nanostructures were synthesized by taking dissimilar precursors for the shell formation. Photoluminescence spectra of prepared QDs corroborate the effectual luminescence. Prepared QDs have large surface area that make them useful alternative as organic antimicrobial agent which are highly irritant and unstable. Study of antimicrobial behavior of QD structures was carried out by disk diffusion method. Antimicrobial study of QDs and their core/shell structures was performed against gram negative and gram positive bacteria, E. coli, A. baumanni and Bacillus subtilis respectively. It is found that elemental composition and size of QDs plays important role in antimicrobial behavior. Prepared QDs are fluorescent and have a key role in complex microbial population studies and identification of bacteria.

Kumari A ，Thakur N ，Vashishtt J ，Singh RR ... -  《-》